LAUSR

BACKGROUND Nivolumab extends the overall survival (OS) of patients with advanced gastric cancer (AGC). Intramuscular adipose tissue (IMAT) is associated with the prognosis of patients with various cancers. We investigated the effect of IMAT on OS in patients with AGC treated with nivolumab. METHODS We enrolled patients with AGC treated with nivolumab (n = 58, 67 years old, men/women 40/18). The subjects were classified into long-term or short-term survival groups according to the median value. The IMAT was evaluated using computed tomography scans at the umbilical level. The decision tree algorithm was employed to reveal the profile associated with prognosis. RESULTS In decision tree analysis, immune-related adverse events (irAEs) were the first divergence variable, and prolonged survival was observed in 100% of patients with irAEs (profile 1). However, long survival was observed in 38% of patients with no irAEs. Among these patients, IMAT was identified as the second divergence variable, and long survival was observed in 63% of patients with high IMAT (profile 2). In patients with low IMAT, only 21% showed prolonged survival (profile 3). Median OS was 717 days (95% confidence interval [CI], 223 to not reached) in profile 1, 245 days (95% CI, 126 to 252) in profile 2, and 132 days (95% CI, 69 to 163) in profile 3. CONCLUSION Immune-related adverse events and high IMAT were favorable factors for OS in patients with AGC treated with nivolumab. Thus, along with irAEs, skeletal muscle quality is important in managing patients with AGC treated with nivolumab.